Past practice has meant the NSA has been helping the Russians, Chinese and terrorists
Any vulnerability the NSA can find, a foreign intelligence agency can find.
The current situation is that the NSA assume nobody inside the USA has any data useful to the Russians, Chinese, Indians, Iranians, Israelis, Pakistanis, Swiss, Germans, British, or terrorists.
And we know from past disclosures the security agencies of all these countries consider international trade and trade secrets somewhat within the purview of their signals intelligence agencies.
Even if the NSA were to start ensuring all US government computers are patched, that still leaves US local and state government, industry, business, academic, and personal computers open to hacking by foreign powers.
The NSA's assumption that US citizens and US businesses have fewer valuable secrets than the Russians or Chinese is invalid. And those US secrets would be valuable to terrorists too.
The NSA must be made to help safeguard Fortress North America and Fortress USA.
By keeping secret vulnerabilities in US local and state government, industry, business, academic, and personal computers -- by keeping Americans vulnerable -- the NSA has been unwittingly helping the Russians, the Chinese and "the terrorists".